1. Field of the Invention
The present invention relates to wireless communications, and in particular, to retransmitting packet data within a wireless communication network.
2. Discussion of the Related Art
Ultra Mobile Broadband (UMB) combines the best aspects of CDMA, TDM, LS-OFDM, OFDM, and OFDMA into a single air interface using sophisticated control and signaling mechanisms and advanced antenna techniques in order to deliver ultra-high fixed and mobile broadband performance.
UMB supports a forward link up to 280 Mbps and a reverse link up to 68 Mbps while mobile and an average network latency of 16.8 msec. Furthermore, voice over IP (VoIP) of up to 500 simultaneous users is facilitated while mobile. Moreover, UMB will enable the convergence of IP-based voice, broadband data, multimedia, information technology, entertainment and consumer electronic services.
UMB can efficiently support OFDMA MAC/Physical and fully support centralized as well as distributed access networks. Inter-access network interfaces are streamlined and fast layer 2 handoff is supported with seamless handoff across air interface revision boundaries.
FIG. 1 illustrates a UMB centralized access network support. As illustrated in FIG. 1, each access terminal (AT) maintains a separate protocol stack for each access network (AN) in the active set, with each protocol stack called a “route.” Furthermore each base station controller (BSC) is a separate AN.
FIG. 2 illustrates a UMB distributed access network. As illustrated in FIG. 2, each AT in this network arrangement maintains a separate protocol stack for each AN in the active set and each cell is a separate AN.
UMB simplifies the inter-AN interface by requiring each AT to support multiple routes. A simpler inter-eBS interface leads to standardized, inter-operable implementations.
Each eBS in the active set uses a separate data route and there is no need to transfer RLP and header compression states between eBSs. Traffic flowing between an eBS and an AT can be tunneled through the serving eBS, thereby supporting fast and seamless re-pointing between cells.
Signaling messages of protocols between an eBS and an AT can be tunneled through the serving eBS. No eBS has to maintain a connection state of other eBSs in the active set.
UMB layering also reduces the number of protocols in the data path. FIG. 3 illustrates UMB layers in which the application layer provides a signaling application, IP, RoHC, EAP and inter-technology tunneling. The radio link layer provides RLP and associated protocols. The MAC layer provides a packet consolidation protocol and control of physical layer channels. The physical layer defines characteristics of air interface channels. The security functions are protocols for ciphering, message integrity, and key exchange. The route control plane controls the creation and maintenance of air interface protocol stacks, one for each eBS. The session control plane provides session negotiation. The connection control plane controls the connection between the AT and an eBS.